5 Troubleshooting
 
5
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Er.234: Runaway
Cause Conrming Methods Corrective Action
1. UVW phase 
sequence is incorrect.
Check whether UVW phase sequence on 
servo drive is consistent with that on motor 
side.
Connect UVW cables according to 
correct phase sequence.
Motor rotor initial phase 
detection is incorrect 
due to interference at 
power-on.
UVW phase sequence is correct. But Er.234 
occurs once servo drive is enabled.
Re-power on the servo system.
3. Encoder type is set 
incorrectly or wiring is 
incorrect.
View servo drive and servo motor nameplates 
to check that the equipment you are using is 
IS650P series servo drive and 20-bit servo 
motor (-U2***) of Inovance.
Replace matching servo drive and 
servo motor. If you use IS650P series 
servo drive and 20-bit servo motor 
(-U2***) of Inovance, ensure that H00-
00 = 14000. Re-conrm motor model, 
encoder type and encoder wiring.
4. Encoder cable is 
incorrectly wired, 
corrosive, or connected 
loosely.
Check whether encoder cable you use is 
standard conguration of Inovance. check 
whether cable is aging, corrosive or is 
connected loosely.
Set the S-ON signal to OFF and rotate motor 
shaft manually. Check whether H0B-10 
(electric angle) changes as motor rotates.
Re-weld, fasten or replace encoder 
cable.
5. When controlling a 
vertical shaft, gravity 
load is too large.
Check whether load of vertical shaft is too 
large. Adjust brake parameters H02-09 to 
H02-12 and then see whether the fault is 
removed.
Reduce load of vertical shaft, improve  
rigidity or shield this fault on the 
prerequisite of not affecting safety and 
use.
On working condition of controlling a vertical shaft or one motor dragging the other, set H0A-
12 = 0 to shield the runaway fault.
Er.400: Main circuit overvoltage
Cause Conrming Methods Corrective Action
1. Main circuit input 
voltage is too high
Check power input specication of servo 
drive. Measure RST input voltage on 
servo drive side and check whether 
input voltage complies with the following 
specication.
220 V AC drive:
Valid value: 220 to 240 V
Allowed error: -10% to 10% (198 to 264 
V)
380V AC drive:
Valid value: 380 to 480 V
Allowed error: -10% to 10% (342 to 528 
V)
Replace power supply or adjust power voltage 
according to specication on the left.
2. Power supply is 
instable or affected 
by the lightning 
strike.
Check whether power supply is instable, 
affected by lightning strike or satises 
preceding specication.
Connect a surge suppressor and then connect 
power supply. If the fault persists, replace the 
servo drive.